Mina Coleman was standing in the driveway of her Tamiami home when she noticed her pack of puppies scrapping over something in the dirt. Vultures circled in the blue sky above. They must have gotten out through that damn hole in the fence again, she thought as she stomped through the backyard. They've probably dug up another dead animal.

When Coleman pulled the dogs apart, however, she didn't find a goat leg or cow rib. Instead, lying in the trampled grass were two bleached bones. Long, thin bones. Human bones.

That was the summer of 1997. Cops would spend weeks investigating, but it would be 14 years before they solved the riddle dug up by Coleman's canines.

Mysterious deaths are common in Miami, a city of runaways and refugees. Each year, several hundred people pass away anonymously -- murder victims cruelly stripped of their possessions, bodies burnt beyond recognition, and vagrants found without ID. Doctors, medical investigators, and homicide detectives are left to piece together their identities.

Many cases take only a few days to solve. Some, like the bones in Tamiami, however, torture investigators for years. Between 1956 and 2009, the ranks of Miami's mysterious dead swelled to more than 300.

But in the past four years, new DNA technology has allowed Miami-Dade medical investigators to whittle down this grisly tally, closing at least 16 cold cases including a 15-year-old suicide and a 27-year-old murder. In doing so, coroners have also given closure to families that had long given up on getting answers. "Each body has its own story," investigator Sandra Boyd says. "But it can't begin until we give them a name."

From the outside, the Miami-Dade Medical Examiner Department looks like a sepulcher. The resemblance is fitting. The boxy brick and concrete building is where anyone who dies under traumatic circumstances -- a murder, suicide, or car accident, for instance -- is delivered before their body can be taken to a funeral home and buried.

In the basement, a team of 11 doctors carves open Miami's dearly departed. The forensic pathologists then slice ­various organs into tiny cubes for toxicological analysis. They pull blood from lifeless veins and fluid from unseeing eyes. Then the doctors sew the bodies back together.

"Mushy brains," one physician says as he uses what looks like a bread knife to carve up a gelatinous blob. Next to him lies the body of a woman. The top of her head is open like the lid of a bear-shaped bottle of honey. She was in a car accident, the doctor explains. "She never had a chance."

"The work can be a little depressing, so they put in a nice skylight for us," says director of operations Larry Cameron, who kept the salt-and-pepper mustache from his previous job as a school principal.

Cameron walks upstairs toward a vast whirring sound. Inside a fluorescent-lighted room are scores of spinning, beeping machines, each one busy analyzing the tissue samples taken in the basement. "This is the lab where the test was run on the infamous MacArthur Causeway guy," Cameron says, referring to Rudy Eugene, the man called the Miami Zombie, who was shot and killed by police last Memorial Day weekend after he ate another man's face. The test results showed Eugene was high on marijuana, not bath salts, as had been widely speculated.

Identifying the dead, however, is a more difficult task than detecting drugs. Jane and John Does are assigned a number and kept in 40-degree coolers, sometimes for years. But they still slowly decompose. State law forbids the cremation of unknown remains, so some skeletons are eventually stripped of their flesh and moved to the "bone room," a vault full of tiny cardboard coffins. Other bodies are buried in Galloway Cemetery, a small park in Southwest Miami-Dade where numbered bricks serve as headstones.